Capital Gains Tax when becoming joint owners on a BTL

My partner and I have a joint residential mortgage for our family home but are currently not married. I have had owned a Buy To Let property solely in my name for about 10 years but have just gifted her part ownership. We have just changed the ownership of the Buy To Let property to joint owners, resulting in my partner being added to the title deeds. She will now have a beneficial interest in the property. Stamp Duty Land Tax was paid for her share of the property when the ownership changed. Am I liable for Capital Gains Tax as I have effectively given a share of my property away? (My partner did not purchase her share, I gifted it to her). If Captial Gains Tax is due, is it based on the original purchase price and half of the current value or is it based on the share of the mortgage? Thanks in advance.

Hi ,
 

Yes as this is seen as a disposal and it is not your main residence and you are not married/civil partners.

 
Thank you .

Not HMRC...value for CGT (your gift of share of let property) would be calculated on you by reference to the difference in cost to the value at date of gift. In this example am assuming now owned 50/50 ownership...so e.g. if bought for £100k and value on gift £150k, gain £50k, gifting (say) 50%, deemed gain liable is therefore £25k...your base cost for the remaining 50% if sold in the future is then half of what you paid i.e. £50k, and your partners base cost if sold in the future is £75k (uplifed to that value as youve already accounted for CGT on the £25k difference and £75k is therefore what your partner was gifted). Mortgages NEVER come in to the equation in calculating gains, they are simply the method of financing the transaction, CGT is ALWAYS by reference to the increase (or decrease for losses) of the asset liable.